Yes a very impressive library. I don’t think I saw a paperback in the collection. (My library has plenty of them)
I’ve got about 20k books about 20% are probably PBs, most of them I’ve gotten from library and estate sales but they go back 50 years to stuff I got as a kid. My wife makes me keep my “trash” in the basement where I’ve installed custom shelfing .... sigh the things you do for love.